def cairo_draw( ctx, width, height ):
    wd = .02 * width
    hd = .02 * height

    width -= 2
    height -= 2

    ctx.move_to (width + 1, 1-hd)
    for i in range(18):
	ctx.rel_line_to (0, height - hd * (2 * i - 1))
	ctx.rel_line_to (- (width - wd * (2 *i)), 0)
	ctx.rel_line_to (0, - (height - hd * (2*i)))
	ctx.rel_line_to (width - wd * (2 * i + 1), 0)

    ctx.set_source_rgb (0, 0, 1)
    ctx.stroke()
